1. Field
The invention is in the field of providing filtered air environments, particularly of providing filtered air to localized areas occupied by persons needing or desiring such environments.
2. State of the Art
There are various situation where an environment of filtered air is desirable. In some manufacturing processes, such as semiconductor manufacture, clean air is required. Such manufacturing usually takes place in clean rooms, entire rooms provided with special high capacity filtering systems that circulate clean air into and through the rooms. However, such rooms are expensive to build and operate so are used only when absolutely necessary. U.S. Pat. No. 5,195,922 discloses a modular system for providing clean room environments in small areas for particular manufacturing equipment. In some instances, the area will be large enough to be entered by a worker.
There are numerous situations where it would be desirable to provide environments with filtered air. In hospitals it is desirable to provide filtered air in operating rooms, in patient recovery areas, and in patient rooms in order to reduce the chance of infection for the patient. In the home and in the work place, filtered air can help people with allergies and asthma. However, the filtered air has to be supplied to the person needing such air or the site where such air is needed without contamination prior to reaching the person or site.
One approach to filtering air in a room is to provide an air filter in the room to circulate the room air through the filter. Room air is drawn into the filter, filtered, and discharged back into the room. Such a filter is shown in U.S. Pat. No. 5,453,049. It is difficult to make much difference in the room air in this way, however, because only a small portion of the air in the room is passed through the filter at any one time and the filtered air from the filter is immediately mixed with room air as it is discharged from the filter prior to reaching the person or localized site needing the filtered air.
U.S. Pat. No. 3,505,989 shows a portable clean room type, sealed enclosure which can be used for medical or other applications where a sterile environment is desired. However, a person is isolated in the enclosure and it is difficult to open and close the seals when entering and leaving the enclosure.
My prior U.S. Pat. No. 6,119,689 shows a canopy over a bed or other work or living area with filtered air supplied to the canopy to fill the canopy. In addition to the hospital uses, such canopy is particularly useful at home for people who suffer from allergies or otherwise desire to sleep in or other be in an atmosphere of filtered air. However, while the canopy is not a sealed space; so may be easily entered and left, and is made of a diaphanous material, many people desire a more open setting rather than being mostly or completely enclosed.
U.S. Pat. No. 3,820,536 shows a filter system which directs a flow of filtered air over a patient undergoing surgery and U.S. Pat. No. 3,724,172 shows a headboard assembly for a hospital bed which creates a flow of filtered air over the patient in a bed. Top and side walls extend a short distance from the headboard. The headboard is designed to provide a relatively high velocity flow of air around the perimeter of a breathing zone to create an air curtain to protect an inner breathing area of slower moving air from contamination.
U.S. Pat. No. 4,872,397 shows a work station having an individual source of air of controlled temperature so a worker can individually control the work station environment. Heated or cooled air from the building heating or air conditioning system is mixed with room air to control temperature. A filter is provided in the system to filter the air in each work station. However, the filtered air is mixed with room air in the work station so the station air is a mixture of filtered and unfiltered air.